Sounds like a good set up. I reccomend Bushmaster.
As to the free float, it will maintain zero better while using a sling, and while builds up in the barrel. I think the weight is about the same, if you use the right tube. Carbon fiber tubes actually reduce weight.

A free float tube like the KAC would add weight becasue of the massive barrel nut. Daniel Defense uses an aluminimum barrel nut and weighs less. M4 double heat shields and a light weight barrel would be the worst combo for barrel heat.
The PRI flip up front sight is actually about the same weight if not less than a standard front sight. The upper half is aluminum and the lower is steel. It lacks a bayonete lug. The lower end has more parts but in the end the weight is a non issue. I would use the PRI just for the awesome sight picture with the HK style hooded front sight but other than that why go folding on a combat rifle? You should have a specific reason to do that.
Also consider this if the rifle is for fighting. If you went with a 1/7 twist barrel that was 14.5" long and used 77 grain ammo instead of M193 you would have the same fragmenting range as a 16" 1/9 twist barrel and the bullets would casue more tissue damage at all ranges. Then your rifle is shorter for CQB handling and lighter too. You would need to get a Bushmaster 1/7 M4 barrel ($195) then send it to Kurt Wala to have it turned to lightweight profile and you could have the Vortex pinned in place to reach 16"
Add to that a RRA flat top upper/bolt/carrier and you have an inexpensive, super light and high out put combat rifle.
I would also suggest the Cav arms single heat sheild copy of the M4 forearm to reduce the barrel heat. Understand it will make it a bit harder to hold after a couple mags though.

good info... thanks.
I was considering the 1:9 twist because I'm not sure what ammo I might have access to down the road and the 1:9 seems to be acceptable for most traditional military bullet weights
Are there any practical differences in heat diassapation, barrel strength, and accuracy between lightweight and fluted barrels.
I'd like to keep it simple, affordable, and rugged so I am leaning towards a traditional fixed front sight settup. That Bushmaster barrel looks like it could fit the bill.
Thanks again

If you insulate your hand from the heat you make the barrel heat up faster and the light weight barrel heats up fastest of all. The best thing to do would be a FF railed forearm for heat disipation and a vertical grip to help in speed and control for combat shooting and the vertical grip makes the heat a non issue.
We are all awaiting the release of the KAC URX which will be the slimiest and lightest FF forearm and dissipate heat the best. But its not here yet. Next best bet for weight and heat dissipation is:
[url]http://www.danieldefense.com/store/view.asp?action=viewproduct&item=9[/url]
but that price is overly high. A Knight's FF RAS is a few ounces more and $50 less. I personally run a KAC FF RAS. I was going to run an M4 handguard too but the added accuracy, modularity, rigidness and heat dissipation made me spend the cash.
The best and lightest vertical grip is:
[url]http://www.tangodownllc.com/product/vertical.shtml[/url]
It has just been released and I have not had the chance to try one but everyone who tries on loves it and its way over engineered.

The FF look great but the price is too prohibitive. I'm just a poor civil servant on a budget. For now, I'll probably have to go with traditional handguards. Do M4 handguards make a big difference over traditional single-shield grips?
I've used vertical foregrips and for semi-auto fire they don't seem to make much of a difference for weapon control. They are nice for keeping the hand away from barrel heat, though.
Thanks again everyone... all good info to chew on.

There is another option.
I love light little carbines. This is a pic of my PWA lower, Bushmaster A1 upper, Colt stock with a Colt 14.5 inch 1/7 light wieght barreled carbine. I love this gun and most of my shooting buddies do as well. It has standard carbine handguards. It is about 5.5 Lbs.
[img]http://www.hunt101.com/img/063183.jpg[/img]
This is an older pic.
[img]http://www.hunt101.com/img/056405.jpg[/img]
Now finding a Colt 14.5 1/7 light weight barrel is a bitch!! And will cost you when you do find it. Well I wanted another one for my tricked out fighting iron. So I bought a 16 inch Colt 1/7 light weight barrel, sent it to KKF had him chop it to 14.5 inches and pin a Vortex on the front of it. I just got the barrel back yesterday. I have not had time to put the upper back together. here are some pics of the barrel and of the rifle before I had the barrel chopped down. 1/7 is the only whay to go these days and light is right.
Before
[img]http://www.hunt101.com/img/054105.jpg[/img]
After
[img]http://www.hunt101.com/img/063156.jpg[/img]
You will loose a little bit of the stamping on the end of the barrel.
[img]http://www.hunt101.com/img/063157.jpg[/img]

Luckystiff,
I'd love to see pics of the chopped down barrel installed.
Are Colt barrels expensive and what did the KKF conversion run you?
_____________
Does anyone have a chart showing velocity of 55/62 gr ammo at 150 yards with 16" and 14.5" barrels?

[url]http://bushmaster.com/faqs/techdatafaqs.asp[/url]
Stick with 55 grain M193.
Colt barrels are very expensive and not worth the price IMHO. You can get a new Bushmaster barrel for less than the cost of a used Colt.

MEH92,
I should have the rifle back together later this week. I have been considering sending the upper to DPMS to have it refinished to match my BLACK PWA lower.
The top pics are of a 14.5 inch light wieght barrel on an A1/C8 upper.
For my trick AR I went with a SIR #50. It gives good ventelation, free foats the barrel and puts rails where I need them without adding a lot of wieght. The other thing that is nice about the SIR "C" models is that you can add or remove them anytime you want. So if you do not have the $$ to get the SIR now you can set your upper up for it in the future but still have use of the rifle in the meantime.
Colt 16 inch LW barrels go anywhere from $200 to $350. Mine has the M4 barrel extention with the M4 feed ramps. The newer Colt carbine barrels have this standard. The work that Kurt did cost me $45 + 12.50 shipping. I supplied the barrel and the Vortex.

I have barrels close to what you are looking for here is a link to mine that is at auction, They are chrome lined 1:9 pre ban and $155.00 shipped to your door. Let me know if I can help! I can get different barrels made if this doesnt cut it.
Robert
[url]www.rbprecision.com[/url]
[url]http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=383&item=3630233117[/url]

Can you get a 1/7 light weight barrel made or just 1/9 barrels? Several people on this board would be willing to purchase 1/7 light weight 4150 chrome lined 5.56 chambered barrels. Are you ordering these up from DPMS or elsewhere?

Originally Posted By DevL:
Can you get a 1/7 light weight barrel made or just 1/9 barrels? Several people on this board would be willing to purchase 1/7 light weight 4150 chrome lined 5.56 chambered barrels. Are you ordering these up from DPMS or elsewhere?

View Quote

I can get the blanks in 1:7 and have them turned, would take some time but sounds like there is interest. I will see what I can get tomorrow and post lead times for completion.
Robert

Originally Posted By Not_A_Llama:
Do you have any similiar deals for post-ban barrels, RPB?

View Quote

I can have these made into post ban versions with the perm attached brakes,(Wilson or RRA styles) takes a couple weeks to make a post ban, the post will be an additional $30.00 with your choice of brake. Let me know if I can help with your projects.
Robert
www.rbprecision.com

I'm dropping off my 1/7" Colt lightweight 16" at the gunsmiths tommorrow for a shortening and Vortex attachment-I've got the older Vortex I've had for a decade or so.
I can't wait to play with it-then I'm adding a Streamlight M-3 to it.

Originally Posted By MEH92:
I'm looking for a new upper for my PWA pre-ban (currently a Commando A2 configuration). Here's the specs I want:
16" M4 flattop profile
chrome chamber/bore
lightweight (fluted or "pencil" profile)
1:9 twist
threaded for Vortex FS
The gun is for fighting, not target shooting, so I want as little weight as possible, but still maintain good structural strength. I also have a budget in the $500 neighborhhood. Any recommedations?
Any other suggestions?
Thank you

View Quote

You described my lightweight setup with the exception of the upper. You didn't mention buttstock. My setup is as follows.
Bushmaster A2 upper
Bushmaster 16" pencil barrel
PWA preban lower
A1 Buttstock
Duckbill grip
SE Vortex FS
A telescoping buttstock would be lighter in weight than A1 or A2.
There is a picture of my carbine in the November issue of SWAT magazine. Its getting a pretty cool Urban Flecktarn camo job.

TWIRE,
I have an A1 stock on it now. It started out with a collapsable stock (unknown manufacturer 3 position) but I didn't like how it wobbled. I also don't think it will stand up to much "socializing" or extraction-malfunction drills (slamming the butt on the ground). I prefer the A1 over the A2.
I also have an ergo grip on it but dicided I didn't like it and will be going back to the original style or duckbill.
I have looked at a few pics of the BM lightweight barrel and it looks like the barrel diameter increases just a little before the threading. Is this right? If so, wouldn't it require adding material after it was cut below 16" so a standard flash supressor would fit correctly?

Originally Posted By MEH92:
I have looked at a few pics of the BM lightweight barrel and it looks like the barrel diameter increases just a little before the threading. Is this right? If so, wouldn't it require adding material after it was cut below 16" so a standard flash suppressor would fit correctly?

View Quote

I know my Colt 14.5" lightweight barrel diameter increases just a little before the threading. I don't know how the lack of this increased diameter would effect a standard flash suppressor.
I have one of these Colt barrels listed for sale/trade in the EE right now. See link:
[url]http://www.weaponforums.com/forums/topic.html?b=7&f=22&t=188776[/url]